No, not really.... This feature was purposefully left out to encourage student responsibility and to reduce the burden on the site administrator. We want our school admins to be out their encouraging students not doing data entry for students/parents who didn't participate in the program but still want credit at the end of the year. Trust us on this one, once the word gets out you can back date miles, participation drops and data entry increases.
That said we do realize there are special extreme situations where this really needs to be done. While not supported, you can [figure it out here]